Status of the treatment of produced water containing polymer in oilfields: A review

Abstract The produced water (PW) generated during chemical enhanced oil recovery (CEOR) in oilfields cannot be treated effectively by traditional wastewater treatment technologies because it is difficult to reduce the viscosity and break the emulsion, causing severe production pressure and environmental issues. The purpose of this review is to provide reference for the development of a novel and high-efficiency treatment technology or methods of PW. In this review, CEOR was introduced, and the components, features, and stability mechanisms of the corresponding PW were summarised. Subsequently, the environmental risk of PW was assessed. The current treatment technologies of PW were discussed systematically, including physical (gravity separation, hydrocyclone separation, and filtration separation), chemical (flocculation and coagulation, surfactant, and demulsifier), physicochemical (air floatation and adsorption), and microbial methods. Moreover, membrane technology was discussed, and finally, some potential research directions and major conclusion involving PW treatment were proposed.